SHOULDER, ARM, FOREARM, HAND. POSTERIOR PART. 363 



median nerve. It gives articular branches to the elbow and wrist, and all subse- 

 quent joints moved by the muscles which it supplies. Demonstrate the dorsal 

 ulnar cutaneous nerve. (Fig. 242.) 



3 . Describe the musculo-spiral nerve. 



It is a branch of the posterior cord of the brachial plexus. (Fig. 42.) It is 

 found between the two humeral heads of the triceps muscle in the musculo-spiral 

 groove with the superior profunda artery. In the lower one-third of the arm it 

 lies between the brachialis anticus and supinator longus. In this place it gives off 

 branches to the radial group of muscles the supinator radii longus, the exten- 

 sor carpi radialis longior and brevior. It divides then into the radial and poste- 

 rior interosseous. The posterior interosseous passes through the supinator 

 b re vis and then supplies the muscles on the posterior part of the forearm. The 

 radial branch becomes cutaneous by piercing the deep fascia in the lower one- 

 third of the forearm, between the supinator longus and the extensor carpi 

 radialis. In the hand the nerve supplies the ball of the thumb and adjacent three 

 and one-half fingers dorsally. (Fig. 242.) The musculo-spiral nerve gives off two 

 cutaneous branches to the skin over the insertion of the triceps and anconeus. 



4. Describe the musculo-cutaneous nerve. 



This is a branch of the outer cord of the brachial plexus. (Fig. 42.) It per- 

 forates, as a rule, the coraco-brachial muscle, and gains the intermuscular space 

 between the biceps and brachialis anticus. It supplies the coraco-brachial and the 

 flexor muscles of the forearm, the biceps, brachialis anticus, and supinator longus ; 

 the cutaneous part is distributed to the skin over the insertion of these muscles. 



5. Describe the circumflex nerve. 



It is a branch of the posterior cord of the brachial plexus. (Fig. 42.) It passes 

 through the quadrangular space to the back of the shoulder with the posterior 

 circumflex artery. (Fig. 249.) It supplies the deltoid and teres minor muscles. 

 It gives two articular branches to the shoulder-joint and cutaneous branches to 

 the skin over the insertion of the deltoid and teres minor muscles. 



6. Name the important regions of geometrical parts in the upper extremity. 

 (i) The radial groove ; (2) the ulnar groove ; (3) the cubital fossa; (4) the 



brachial groove ; (5) the axilla ; (6) the quadrangular space (7) the first tri- 

 angular space ; (8) the second triangular space. 



7. Give t/ic special names for deep fascia in the tipper extremity. 



(i) Anterior annular ligament; (2) posterior annular ligament ; (3) dorsal 

 fascia ; (4) palmar fascia ; (5) ligamenta vaginales ; (6) bicipital fascia ; (7) axillary 

 fascia; (8) clavi-pectoral fascia; (9) costo-coracoid ligament; (10) pectoral apo- 

 neurosis ; (11) deltoid aponeurosis ; (12) supraspinous fascia ; (13) infraspinous 

 fascia ; (14) superior transverse scapular ligament ; (i 5) inferior transverse scapu- 

 lar ligament. (Fig. 252.) 



8. What structures did you find under the anterior annular ligament at the 

 carpus ? 



(i) The flexor sublimis digitorum ; (2) the flexor profundus digitorum ; (3) 

 the flexor longus pollicis ; (4) the median nerve and its artery. 



9. Give boundaries of the radial groove, and its contents. 



On the radial side is the supinator longus muscle ; on the ulnar side, in the 

 upper third, the pronator radii teres ; in the remainder of its course, the flexor 

 carpi radialis. In front of the artery the skin and fasciae form the roof of the 

 radial groove. Behind the artery, from above, are : (i) The biceps ; (2) supinator 

 brevis ; (3) pronator radii teres ; (4) flexor sublimis digitorum ; (5) flexor longus 

 pollicis ; (6) pronator quadratus ; (7) a small part of the lower end of the radius. 

 The radial groove contains the radial artery and its vena; comites. 



10. Give boundaries and contents of the ulnar groove. 



The ulnar groove contains the ulnar artery and its venae comites. The artery 



